Pole construction



S. H. MORTENSEN. POLE CONSTRUCTION. APPLICATION FILED JuL Y 18.1318.

Patented; Oct, 12,1920.

a b 7 w a PPATENT OFFICE.

UNITEB STATEE SOREN H. MIORTENSEN OF lJZILRVAUKEE, FTISOO 'S MANUFACTURING OOIVLEAN'Z, MILNAU DELAWARE.

Application filed July 18, 1918.

To all whom it may concern Be it known that l, SOREN H. MonrnNsnN, a citizen of the United States, residing at Milwaukee, in the county of Milwaukee and State of Wisconsin, have invented a certain new and useful Improvement in Pole Gonstructions, of which the following is a specification. V

This invention relates to magnetic field structures and the pole pieces thereof and may be applied in dynamo-electric machines. A particularly advantageous use of the invention is in large alternating current generators having revolving iield structure In large machines in which revolving magnetic field structures are used having projecting pole pieces very considerable stresses arise chiefly by reason of centrifugal force tending to tear the pole pieces awa T from the core in which they are fastened. it is usual to construct such pole pieces with a plurality of means for fastening the same to the core in order to give sutlicient strength to resist the forces developed. is however found that with he usual accuracy of workmanship the several fastening means will not assume the same share of the stress developed. if for example, one of the fastening means is slightly looser than another, the portion of the pole piece with which the loose fastening means is associated will tend to move outwardly under centrifugal stresses and this force will be transmitted as a bending moment to one of the other fastening means associated with the pole piece. The result is that the fastening means upon which the bending moment is exerted is liable to break or to cause breakage of the core. One of the objects of the invention is the provision of a field pole structure of safe construction which will obviate the dangers hereinbefore noted.

Another object of the invention the appear from this specification and the ac- Specification of Letters Patent.

IN, ASSIGNOR T0 ALLIS-CHALMERS Patented Oct. 12, 1920.

Serial No. 245,963.

companying drawings which form a part thereof and all these novel features are intended to be particularly pointed out in the claims.

In Figure 1 is shown a field structure embodying the features of the invention, the same being a section along the line 1-1 in the direction of the arrows.

Jig. 2 is a plan view of a field structure embodying the features of the invention looking in the direction of the face of the pole piece, the revolving core portion being partly broken away.

Fig. 3 is a modification of the form of laminae shown in Fig. 1.

The core 1 of the revolving field structure, a fragment of which is shown in Fig. 1, may be supported by any desirable form of spider, (not shown). The core 1 has a plurality of recesses 2, 3 therein, here shown as of dove-tail form.

The pole 8 comprises a plurality of parts 4-, 5, here shown as made up of separate sets of laminae. Each lamina has a projection 6, '7 that is here shown as of dovetail form. it is not essential that the pole piece parts be fastened to the core by dove-tail joints; any suitable fastening means may be used. Each lamina of one set also has a pole tip portion 9, the pole tip portion 10, of the other set of laminae extending in the reverse direction when the sets are assembled on the core 1. Each set of laminze is held together by end plates 11-12, 1314 respectively. The means for holding the plates and laminae together may be of any desirable construction such as riveted rods or bolts passing through the holes 19, 20 in the laminae. The end plates are provided with lateral extensions 15, 16, 17, 18. The lateral extensions in conjunction with the pole tips serve to hold the winding 21 in place, the latter being drawn up tightly against the .core 1 when the parts a, 5 of the pole piece are drawn tightly against the core 1 by any suitable wedging or holding means 22-, 23 in recesses 2, 8. It will be noted that the inner surface of the coil 21 is spaced from the outer surface of the parts 4, 5 of the pole piece and for the purpose of centering the coil properly means such as spacers 28, 29 may be used.

A space 24 left bet. een the separate portions i 5 of the pole piece serves as a sin"- able ventilating passage in conjunction with holes 25, 26, 27 any suitable number of which may be provided in core 1. Other holes 30, 31 affording other passages may also be provided in the core for communicating with the space between the winding and the pole piece existing between the spacers 28, 29. In order that ventilating fluid may escape from the said space and passages, a number of the pole tip portions of the laminae may be omitted to leave spaces 32. Inasmuch as the spacers 28, 29 would baffie the passage of ventilating fluid between them to the spaces 24, 32, an additional set ofholes 35 in the extensions on the end plates may be provided.

In order to balance against each other the centrifugal forces arising in the pole tips 9, 10, a number of the laminae may be provided with. extensions 86 adapted to'touch each other when the halves of the pole piece are assembled. This construction does not prevent a relative sliding movement between the pole-halves.

It will be seen that the pole piece portions are substantially independent and that the dies necessary for stamping the laminae composing the same will be much less expensive. Furthermore, as a result of this construction in which separate end plates are used for the separate pole piece portions, objectionable forces arising in one of these portions cannot be transmitted to a fastening means associated with another portion.

The fact that the parts 4, 5 can be drawn up to the core 1 separately makes a better magnetic joint possible. Furthermore the construction lends itself readily to the proper ventilation of not only the pole piece itself and the surrounding coil, but also the stator of the machine. In this connection it will be noted that the air thrown out by centrifugal force through the passage 25, 2 1 will serve to cool the stator.

In the case of very large pole constructions, it may become advisable to add strength to the fastening means for the pole piece portions and this may be done if desired in the manner illustrated in Fig. 3 in which the parts 41, 51, 61, 71 correspond to the parts 4, 5, 6, 'Z of Fig. l and in which a half-dove-tail projection 33, 84; has been added to each of the juxtaposed laminae ref sired that the invention claimed be limited to the exact details of construction as shown and described for obvious modificatlons Wlll occur to a person SklllGCl 1n the art.

It is claimed and desired to secure by Let- 7 V ters Patent: 1

1. In combination a core, a pole for said core hav'ing'pole tips, and being composed of laminae, a number of the lamina being formed without pole tip portions,-a win-ding surrounding and spaced from said pole and held by said pole tips, said core having passages communicating with said'space to provide ventilation for said winding and pole. V

2. In a dynamo-electric machine of the type having a stator and a revolving field, a core for said field,'a pole for said core comprising a plurality ofseparate parts juxtaposed and spaced apart along substantially their entire length and in contact only near the face of said pole.

3. In a dynamo-electric machine of the type having a stator and a revolving field,

a core for said field, a pole for said core'coniprising a plurality of separate parts juxtaposed and spaced apart along substantially their entire length and in substantially radial-sliding contact near the face of said pole.

4. In a dynamo-electric machine of the type having a stator and a revolving field,

a core for said field, a pole for said core comprising a plurality of separate parts, said parts being in force-transmitting relation, with respect to each other, in a circumferential direction near the face of said pole, and means for fastening each part separately to said core. 7

In testimony whereof the signature of the inventor is aflixed hereto.

SOREN H. MQRTENSEN. 

